Conventional pliers use a moving pivot between the members. That is, a projection extends from one of the members between the jaw and the handle. There is a complimentary slot on the other member in which the projection moves. Because the projection acts both as the pivot point and as the variable adjustment, it has a tendency to slip when in use. This is extremely annoying and can be dangerous at times.
Prior art devices, such as, U.S. Pat. No. 644,825 to P. Jensen, uses various pivots and handles. In the Jensen patent, three handles are used along with two pivot points. There is no movable pin in a slot.
In U.S. Pat. No. 5,176,048 to Jore et al., a pin and slot arrangement is used, but there is no projection and pivot surface about which the projection pivots. Thus, the jaws have a narrowed range of motion of its opening relative to this invention. Both above-noted patents are incorporated herein by reference.
This invention has the advantage of providing a wide variable range of movement of the jaws by the combination of a projection that cams about one ore more pivot surfaces and a pin movably secured in a slot. The projection extends from one member and abuts against a pivot area of the other member in a fashion which allows the members to move relative to one another in a scissors fashion. The location of the projection and pivot surface relative to the jaws and handles of the pliers determines the mechanical advantage thereof. The pin extends from one member through a slot in the other member and has a head or other device for holding it in the slot while permitting relative motion of the members. This combination gives secure movement of the members while allowing a wide range of travel of the jaws. Alternate embodiments of this invention utilize a plurality of pivot areas or pivot notches to engage the projection. Differently-shaped jaws may be used to grasp specialized items.